A Sheet and an Optical Fingerprint Scanner

ABSTRACT

A sheet for optical fingerprint recognition or input, and a device including such a sheet. The sheet can detect fingerprint information having high contrast with a simple structure and can be applied to a large area display device to recognize a plurality of fingerprint patterns without being influenced by each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 271of International Application No. PCT/KR2017/013934, filed Nov. 30, 2017,published in Korean, which claims priority from Korean PatentApplication No. 10-2016-0162148 filed on Nov. 30, 2016 and Korean PatentApplication No. 10-2017-0145403 filed on Nov. 2, 2017, all of which areincorporated herein by reference.

TECHNICAL FIELD

The present application relates to a sheet usable for opticalfingerprint recognition and a device comprising the same.

BACKGROUND ART

Depending on generalization and use frequency increase of portablemobile devices such as smartphones and tablet PCs, security of thesedevices is becoming more important. Especially, it is more important tomaintain security in electronic commerce and banking fields using thesedevices. Biological information of a user, for example, fingerprint,iris, face, or voice, can be used to identify or authenticate a deviceuser for security maintenance. In recent years, portable mobile devicesto which a user authentication technology through the fingerprint isapplied have also been commercialized.

On the other hand, fingerprint recognition methods can be classifiedinto an optical method, an ultrasonic method, an electrostatic capacitymethod, an electric field measurement method and a heat sensing method,and the like. Among these, the optical fingerprint recognition methodcan be divided into a so-called scattering method for detecting lightscattered in a ridge portion of a fingerprint in direct contact with atransparent fingerprint contact portion of the device, and a so-calledtotal reflection method for detecting light totally reflected from thesurface of a fingerprint contact portion corresponding to a valleyportion of a fingerprint. In the former case, since light to bescattered must be detected, it may be difficult to provide a lightquantity sufficient to identify the fingerprint pattern to the sensor,and the path of the scattered light may overlap the light path of theoriginal light source, so that the contrast may be lowered. And, in thescattering method, a trapezoidal distortion caused by the light pathdifference also occurs. Devices having various structures have beenproposed to solve the above problems through various papers and patents,but it cannot be said that the scattering method is not suitable forportable mobile devices because of the use of bulky prisms or the like.Also, in the latter case, there is an advantage that a greater lightquantity can be secured than a method of detecting scattered light, butif the total reflection path is long in the process in which the totallyreflected light toward the sensor repeats the total reflection along thewaveguide, the lights totally reflected from adjacent fingerprints mayinterfere with each other to lower the contrast. In addition, when theconventional total reflection method is used, the size of the device canbe increased due to the necessity of separately installing a sensor or aprism, and the like, and there is a problem that compatibility with theportable mobile device having a large area display is also poor, becauseinput and output structures of the fingerprint recognition device arevery limited, as the sensor is positioned at the opposite end of one endof the waveguide where the light source is positioned.

DISCLOSURE Technical Problem

It is one object of the present application to provide a sheet foroptical fingerprint recognition capable of detecting fingerprintinformation with high contrast and a device comprising the same.

It is another object of the present application to provide a sheet foroptical fingerprint recognition which has a simple structure and iscapable of simultaneously recognizing a plurality of fingerprints in alarge area, and a device comprising the same.

The above objects of the present application and other objects can beall solved by the present application which is described in detailbelow.

Technical Solution

In order to solve the problems of the prior art described above and toachieve the above objects, the present application provides a sheetcomprising, in a single layer, a first light control part capable ofproviding light always totally reflected from a surface layer of thesheet; and a second light control part capable of providing light whosetotal reflection is determined according to a fingerprint pattern incontact with the surface layer of the sheet to the surface layer of thesheet by changing a part of the light provided from the first lightcontrol part and totally reflected from the surface layer of the sheetat a predetermined angle and emitting it, and a device thereof.

Advantageous Effects

The present application can provide a sheet for optical fingerprintrecognition that can provide fingerprint information with high contrastand recognize a plurality of fingerprint patterns without any influenceon each other. In addition, the present application can provide a devicecapable of having a large-area sensor and a screen display devicewithout being restricted by incidence and emission structures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows a cross-section of a sheet for opticalfingerprint recognition according to one embodiment of the presentapplication and a device comprising the same.

FIG. 2 is an image of a fingerprint photographed using a sheet accordingto one embodiment of the present application.

Hereinafter, a sheet according to one embodiment of the presentapplication and a device comprising the same will be described in detailwith reference to the accompanying drawings. For ease of explanation,the size or shape of each configuration shown may be exaggerated orreduced.

DETAILED DESCRIPTION OF THE DRAWINGS

In one example related to the present application, the presentapplication relates to a sheet for optical fingerprint recognition or asheet for fingerprint input. As described below, the sheet of thepresent application can be configured so that light derived from anexternal light source can be present (incident) on the sheet surfacelayer with two lights (rays) with different angles. One of the lights(rays) can be always totally reflected in the sheet, and the other canbe identified by the sensor positioned on the lower part of the sheet,by being determined for total reflection at the surface layer of thesheet depending on a pattern of a material contacting the outside of thesheet, and reaching the lower part of the sheet or penetrating the sheetafter being totally reflected.

In this regard, FIG. 1 schematically shows a cross-section of a sheet600 for optical fingerprint recognition (or input) according to oneembodiment of the present application and a device comprising the same.The present application will be described with reference to FIG. 1 asfollows.

The sheet 600 of the present application may comprise a lower base layer300 and a light control layer 200 positioned on the lower base layer300. In the present application, the term “on” or “above” used inconnection with the interlayer lamination position may mean includingnot only the case where a configuration is formed directly on anotherconfiguration but also the case where a third configuration isinterposed between these configurations.

The light control layer 200 comprises a first light control part 210 anda second light control part 220. The light control parts 210, 220 may beconfigurations provided so as to perform a predetermined function onlyon light incident at a specific angle. Accordingly, as described below,the first light control part 210 can provide light that always totallyreflects to the surface layer of the sheet 600. Furthermore, the secondlight control part 220 can provide to the surface layer of the sheetlight in which the total reflection is determined depending on afingerprint pattern in contact with the sheet surface layer.

As shown in FIG. 1, the first light control part 210 can emit the lightincident at a first incident angle (θ₀) with respect to the lowersurface of the first light control part 210 as the light (A) with asecond incident angle (θ_(A)) different from the first incident angle(θ₀). In one example, the exit surface or the exit region of the firstlight control part 210, from which the light with the second incidentangle (θ_(A)) is emitted, may be any other surface or any inside regionother than the lower surface of the first light control part 210. Morespecifically, the sheet 600 of the present application can be configuredso that the light with the second incident angle (θ_(A)) can be emittedfrom the side surface and/or upper surface of the first light controlpart 210 or any region and/or point inside the first light control part210. In addition, the second light control part 220 can emit the lightincident at a second incident angle (θ_(A)) with respect to the uppersurface of the second light control part 220 as the light (A) with athird incident angle (θ_(A)) and the light (B) with a third incidentangle (θ_(B)) different from the second incident angle (θ_(A)). In oneexample, the exit surface or the exit region of the second light controlpart 220, from which the light with the second incident angle (θ_(A))and the light with the third incident angle (θ_(B)) are emitted, may beany other surface or any inside region other than the lower surface ofthe second light control part 220. More specifically, the sheet 600 ofthe present application can be configured so that the light (A) with thesecond incident angle (θ_(A)) and the light (B) with the third incidentangle (θ_(B)) can be emitted from the side surface and/or upper surfaceof the second light control part 220 or any region and/or point insidethe second light control part 220. In the present application, the unitof angle is ° (degree), and the term “incident angle” is an angle formedby the traveling direction of light from the normal to the sheet (orlight-entering layer or light-entering surface) placed on the horizontalplane, which may have more than 0° to less than 90°. The term incidentangle may also be referred to as an exit angle depending on the relativeposition of each configuration along the traveling direction of light.In the present application, the “lower surface” may mean one surface ofa transparent base layer, a light control layer or a light control partwhich faces or contacts the lower base layer, and the “upper surface”may mean the opposite one surface of a transparent base layer, a lightcontrol layer or a light control part, having the relevant lowersurface. The lower surface or the upper surface may be referred to as alight-entering surface or an incident surface, and a light-emittingsurface or an exit surface, depending on the traveling path of light.

Since the light control layer 200 of the present application can bedivided into two parts in which the angle or path of light, and the likecan be controlled differently from each other as above, two lights (Aand B) having different angles toward the transparent base layerpositioned on the light control layer 200, specifically, with respect tothe transparent base layer, and more specifically, with respect to thesurface layer of the sheet 600, can be provided (emitted), as in FIG. 1.In the present application, the surface layer of the sheet may mean, forexample, the upper surface of the transparent base layer in contact withair, or the upper surface of the transparent base layer in direct orindirect contact with an object having a pattern such as a fingerprint.

In one example, the sheet 600 of the present application may furthercomprise a transparent base layer that a fingerprint can contactdirectly or indirectly. When the sheet 600 comprises a transparent baselayer, the transparent base layer may be located on the light controllayer 200. That is, the sheet 600 may sequentially comprise a lower baselayer 300, a light control layer 200 and a transparent base layer. Inthe present application, the term “transparent” used in relation to theproperties of a configuration such as the layer may mean a case wherethe lower limit of the transmittance to visible light having awavelength of 380 nm to 780 nm is 65% or more, 70% or more, 75% or more,80% or more, 85% or more, 90% or more, or 95% or more, and the upperlimit is about 100%, which is in a range of less than 100%.

In the case of comprising the transparent base layer, the first lightcontrol part 210 can emit the light incident on the lower surface of thefirst light control part 210 at the first incident angle (θ₀) throughthe lower base layer 300 as the light with the second incident angle(θ_(A)) different from the first incident angle (θ₀) toward thetransparent base layer. That is, the first light control part 210 canconvert light incident at the first incident angle (θ₀) with respect tothe lower surface thereof into light with the second angle (θ_(A)) toprovide totally reflected light in the sheet 600. In one example, thelight with the second incident angle (θ_(A)) can be emitted from theupper surface and/or the side surface of the first light control part210. Furthermore, when the transparent base layer is directly positionedon the light control layer 200, the lower surface of the transparentbase layer can be the light incident surface with respect to the lightwith the second incident angle (θ_(A)).

In the case of comprising the transparent base layer, the second lightcontrol part 220 can emit the light incident on the upper surface of thesecond light control part 220 at the second incident angle (θ_(A))through the transparent base layer after being totally reflected as thelight (A) with the second incident angle (θ_(A)) and the light (B) withthe third incident angle (θ_(B)) different from the second incidentangle (θ_(A)) toward the transparent base layer. In one example, thelight with the second incident angle (θ_(A)) and the light with thethird incident angle (θ_(B)) can be emitted from the upper surfaceand/or the side surface of the second light control part 220. That is,the second light control part 220 can convert a part of the light (A)having an incident angle of θ_(A) into the light (B) having an incidentangle of θ_(B). The conversion degree, that is, the ratio, in which thelight (A) incident at the angle θ_(A) is converted to the light (B) withthe angle θ_(B), is not particularly limited, which may be suitablyadjusted in a range of more than 0% to less than 100%. At this time,θ_(A) and θ_(B) may be an (incident) angle that the light emitted fromthe first light control part 210 and the light emitted from the secondlight control part 220 have each in the inside of the transparent baselayer.

The information of the fingerprint 700 in contact with the transparentbase layer can be read by the above configuration. Specifically, a pathof light for allowing the fingerprint information to be read accordingto one example of the present application will be described as follows.That is, the light incident on the first light control part 210 from thelight source via the lower base layer 300 is emitted as the light withthe angle θ_(A) that can be always totally reflected from the uppersurface of the transparent base layer into the inside of the sheet 600by the first light control part 210, and the light with the angle θ_(A)emitted from the first light control part 210 is totally reflected fromthe upper surface of the transparent base layer irrespective of whetheror not the fingerprint 700 and the transparent base layer contact, andis incident on the second light control part 220. And, the second lightcontrol part 220 converts a part of the light incident at the angleθ_(A) into the light with the angle θ_(B) and emits the light to thetransparent base layer, and the remaining unconverted light is totallyreflected from the upper surface of the lower base layer 300, forexample, the interface between the light control layer 200 and the lowerbase layer 300. Thereafter, the light with the angle θ_(B) emitted tothe transparent base layer is transmitted from the ridge 710 of thefingerprint 700, which is a contact portion of the transparent baselayer and the fingerprint 700, and is totally reflected from the valley720 of the fingerprint 700, which is a non-contact portion of thetransparent base layer and the fingerprint 700. The light with the angleθ_(B) totally reflected from the valley portion of the fingerprint 700and the transparent base layer and the fingerprint 700 can pass throughthe light control layer 200, reach the lower base layer 300 or penetrateit, and reach the sensor to be identified. In the present application,the term “interface” may mean a boundary surface between two adjacentlayers, or a boundary surface between heterogeneous media placed on apath through which light passes. In addition, when the light with theangle θ_(B) penetrates the upper surface of the transparent base layerfrom the ridge 710 of the fingerprint 700, scattering and/or reflectionmay occur together with transmission.

According to one embodiment of the present application, in order toperform functions as above, the sheet of the present application may beconstituted or provided as follows.

In one example, the first light control part 210 and the second lightcontrol part 220 may comprise each a diffractive optical element or arefractive optical element.

The refractive optical element may mean an element having acharacteristic in which the traveling direction or angle of light isdetermined by the refractive index difference with the adjacent medium.When the light control part of the present application is a refractiveoptical element, the light control part may be configured inconsideration of refractive indexes between the respective layers so asto satisfy the optical path described in the present application.

The diffractive optical element may mean an element having acharacteristic in which the traveling direction or angle of light isdetermined by the shape of the pattern and the spacing between thepatterns. When the light control part of the present application is adiffractive optical element, the light control part may be configured inconsideration of refractive indexes between the respective layers anddiffraction patterns so as to satisfy the optical path described in thepresent application.

In one example, the light control layer 200 of the present applicationmay comprise a diffractive optical element. Specifically, the firstlight control part 210 and the second light control part 220 maycomprise diffractive optical elements having different functions fromeach other, where the diffractive optical element may be a holographicoptical element (HOE) in the form of a film. The holography is atechnique for recording an interference pattern in a photosensitivemedium to reproduce a three-dimensional image called a hologram. Also,the holographic film may mean a film on which a holographic recording isrecorded, and may mean a film capable of recording an interferencepattern on a film having very small photosensitive particles usingrecording light and reproducing it using reproduction light. Since theholographic film may perform the function only for the recorded lightand may not perform the required function for light other than therecorded light, when the holographic film is used for the first lightcontrol part 210 and the second light control part 220, it isparticularly advantageous to adjust the angle, the optical path and/orthe light quantity of light required in the present application.

The holographic film may comprise a photosensitive material as arecording medium. As the photosensitive material, a photopolymer, aphotoresist, a silver halide emulsion, a dichromated gelatin, aphotographic emulsion, a photothermoplastic or a photorefractivematerial, and the like can be used. In one example, the holographic filmmay comprise a photopolymer as a photosensitive material, and may be,specifically, a film consisting only of a photopolymer, or a film with adouble-layered structure comprising a photopolymer layer and a substratefor the layer together. In this case, the substrate used together withthe photopolymer may be a transparent substrate and may be, for example,a substrate comprising polycarbonate (PC), polypropylene (PP), polyamide(PA), polyethylene terephthalate (PET) or triacetyl cellulose (TAC), andthe like, but is not particularly limited.

In one example, the diffraction efficiencies of the first light controlpart 210 and the second light control part 220 may be the same ordifferent from each other. Specifically, the first light control part210 may have the same diffraction efficiency in its entire area and thesecond light control part 220 may also have the same diffractionefficiency in its entire area, where the diffraction efficiencies of thelight control parts 210, 220 may be the same or different from eachother.

In one example, the first light control part 210 and the second lightcontrol part 220 may be some regions formed by changing only angles ordiffraction patterns of recording light on one layer, respectively.Alternatively, the light control layer 200 may also be formed bydirectly attaching the first light control part 210 and the second lightcontrol part 220 or by attaching them via another medium, so that thefirst light control part 210 and the second light control part 220,which are separately manufacture, may form a single layer.

When the transmittance described above is satisfied, the kind of thetransparent base layer is not particularly limited. For example, it maycomprise glass or a polymer resin. As the polymer resin, a polyesterfilm such as PC (polycarbonate), PEN (poly(ethylene naphthalate)) or PET(poly(ethylene terephthalate)), an acrylic film such as PMMA(poly(methyl methacrylate)) or a polyolefin film such as PE(polyethylene) or PP (polypropylene) may be used, without being limitedthereto. In one example, the transparent base layer may have aconfiguration in which a number of glass or polymer resins arelaminated. Even in the case of having such a laminated structure, thetransparent base layer may be provided so as to perform the functionsrequired in the present application and satisfy the following relationalexpressions.

In one example, the lower base layer 300 may be a pressure-sensitiveadhesive layer satisfying refractive indexes to be described below andrelational expressions to be defined in the present application. Thekind or composition of the pressure-sensitive adhesive layer is notparticularly limited and may be, for example, an acrylicpressure-sensitive adhesive layer or a silicone pressure-sensitiveadhesive layer. In another example, the lower base layer 300 may furthercomprise, in addition to the pressure-sensitive adhesive material, theabove-described transparent resin film, where these may function as asubstrate for the pressure-sensitive adhesive material, or may be usedfor the purpose of imparting other functions. Even in the case of havingsuch a configuration, the lower base layer 300 may be provided so as toperform the function required in the present application and satisfy thefollowing relational expressions.

In the present application, the lower base layer 300, the light controllayer 200 and the transparent base layer may have the same or differentrefractive indexes. In one example, the layers may each independentlyhave a refractive index in a range of more than 1 to 5 or less, or morethan 1 to 3 or less, and the interlayer refractive index difference maybe 0.0001 to 2 or less. In the case of the light control layer 200, therefractive indexes of the first light control part 210 and the secondlight control part 220 can be adjusted to be the same or different in arange that can perform the functions required in the presentapplication.

In one example, the refractive index of the lower base layer 300 may beless than the refractive index of the light control layer 200 and/or therefractive index of the transparent base layer. That is, the lower baselayer 300 may be a low refractive layer. Although not particularlylimited, when the refractive index relationship is satisfied, therefractive index difference between the lower base layer 300 and thelight control layer 200 may be 0.1 or less.

In one example, the transparent base layer may have a higher refractiveindex than the light control layer 200. Although not particularlylimited, when the refractive index relationship is satisfied, therefractive index difference between the transparent base layer and thelight control layer 200 may be 0.05 or less.

In the present application, the thicknesses of the lower base layer 300,the light control layer 200, the transparent base layer, or otherconstituents that may be contained therein is not particularly limited.For example, if the function of the sheet described in the presentapplication is exerted, the thickness of the structure is not limited,where for example, the lower limit may be 0.1 μm or more, or 1 μm ormore and the upper limit may be 1,000 μm or less or 500 μm or less.

The sheet 600 of the present application may be configured such that thelight with the angle θ_(A) always totally reflected in the sheet 600 maybe present. That is, the light with θ_(A) can be always totallyreflected from the upper surface of the transparent base layer, and thelight with θ_(A) can also be totally reflected from the upper surface ofthe transparent base layer, can pass through the light control layer 200from the transparent base layer and can be totally reflected from theupper surface of the lower base layer 300, for example, the interfacebetween the light control layer 200 and the lower base layer 300.

Specifically, the sheet 600 of the present application can be configuredso that the light with the angle θ_(A) emitted from the first lightcontrol part 210 toward the transparent base layer satisfies thefollowing relational expressions 1 and 2. The relational expressionsdescribed below can be obtained using Snell's law.

θ_(A)>(180°/π)×sin⁻¹(n ₀ /n ₁)  [Relational Expression 1]

Relational Expression 1 above exemplarily defines the condition that thelight with the angle θ_(A) traveling from the transparent base layer tothe air side is totally reflected from the upper surface of thetransparent base layer, for example, the interface between thetransparent base layer and the air layer. In Relational Expression 1above, n₀ is 1 as the refractive index of air, and n₁ is the refractiveindex of the transparent base layer.

θ_(A)>(180°/π)×sin⁻¹(n ₃ /n ₁)  [Relational Expression 2]

Relational Expression 2 above exemplarily defines the condition that thelight with the angle θ_(A) totally reflected from the upper surface ofthe transparent base layer passes through the light control layer 200from the transparent base layer and is totally reflected from the uppersurface of the lower base layer 300 such as the interface between thelight control layer 200 and the lower base layer 300. In RelationalExpression 2 above, n₁ is the refractive index of the transparent baselayer, and n₃ is the refractive index of the lower base layer 300.

In one example, in order to satisfy Relational Expression 2 above, thelight with the angle θ_(A) totally reflected from the upper surface ofthe transparent base layer must penetrate the transparent base layerand/or the upper surface of the light control layer 200. For example,when the refractive index of the transparent base layer is larger thanthe refractive index of the light control layer 200, the totalreflection should not occur at the upper surface of the light controllayer 200, for example, the interface between the transparent base layerand the light control layer 200, and thus θ_(A) must satisfy thefollowing relational expression 3.

θ_(A)<(180°/π)×sin⁻¹(n ₂ /n ₁)  [Relational Expression 3]

Relational Expression 3 above exemplarily defines the condition that thetotal reflection does not occur at the interface between the transparentbase layer and the light control layer 200. In Relational Expression 3above, n₁ is the refractive index of the transparent base layer, n₂ isthe refractive index of the first light control part 210 or the secondlight control part 220 in the light control layer 200, and n₁ is largerthan n₂.

In the present application, the light with the angle θ_(A) may be lighttotally reflected from the upper surface (contact surface) of thetransparent base layer where the transparent base layer and an objectcontact directly, even when the object having a pattern with a differentheight contacts the transparent base layer. In order to satisfy this,the angle θ_(A) of the light emitted from the first light control part210 may satisfy, for example, the following relational expression 4.

θ_(A)>(180°/π)×sin⁻¹(n _(h) /n ₁)  [Relational Expression 4]

In Relational Expression 4 above, n₁ is the refractive index of thetransparent base layer, and n_(h) is the refractive index of the portionwhose the object having a pattern with a different height is in directcontact with the transparent base layer. At this time, the object havinga pattern with a different height may be a fingerprint 700 and theportion whose the object having a pattern with a different height is indirect contact with the transparent base layer may be a ridge 710 of thefingerprint 700. On the other hand, the non-contact portion of theobject having a pattern with a different height with the transparentbase layer may be a valley 720 of the fingerprint 700, and since thevalley portion is occupied by the air, the refractive index of thevalley portion can be regarded as 1 (=n₀).

As described above, in the present application, the sheet 600 isprovided so as to be capable of providing the totally reflected lightalways totally reflected in the sheet 600 so that the light with theangle (θ_(A)) provided from the first light control part 210 satisfiesthe predetermined relational expressions. On the other hand, in thepresent application, the light with the angle (θ_(A)) is light in whichthe total reflection is performed irrespective of whether or not thefingerprint 700 contacts, so that the light quantity in the sheet 600can be maintained at a certain level. And, as described below, since thelight with the angle (θ_(B)) used for fingerprint recognition originatesfrom the light with the angle (θ_(A)), the light with the angle (θ_(B))for generating the fingerprint image can also have a light quantity keptconstant in the sheet 600 irrespective of whether or not the fingerprint700 contacts.

In the present application, the second light control part 220 may be aconfiguration to provide light (B) generated regardless of whether ornot the fingerprint 700 contacts.

Specifically, the second light control part 220 may be a configurationto provide light with an angle (θ_(B)) at which the total reflection onthe upper surface of the transparent base layer is determined dependingon the presence or absence of an object existing on the transparent baselayer. That is, the light with the angle (θ_(B)) may be light that whenthe object does not exist on the transparent base layer, it is totallyreflected from the upper surface of the transparent base layer, forexample, the interface between the transparent base layer and the air,but when the object having a pattern with a different height contactsthe transparent base layer, it is transmitted (or transmission,scattering, and reflection can occur at the same time) from a directcontact portion (ridge) of the object with respect to the transparentbase layer.

In one example, the sheet 600 of the present application may be providedso that the light with the angle (θ_(B)) may be totally reflected fromthe upper surface of the transparent base layer, for example, theinterface between the transparent base layer and the air, by satisfyingthe following relational expression 5. And, when the object having apattern with a different height contacts the transparent base layer, itmay be configured so that the light with the angle (θ_(B)) may betransmitted (or transmission, scattering, and reflection can occur atthe same time) from the upper face portion of the transparent base layerin direct contact with the object, by satisfying the followingrelational expression 6.

θ_(B)>(180°/π)×sin⁻¹(n ₀ /n ₁)  [Relational Expression 5]

θ_(B)<(180°/π)×sin⁻¹(n _(h) /n ₁)  [Relational Expression 6]

In Relational Expressions 5 and 6 above, n₀ is 1 as the refractive indexof air, n₁ is the refractive index of the transparent base layer, andn_(h) is a refractive index of a ridge portion in direct contact withthe transparent base layer in the object having a pattern with adifferent height. As described above, since the valley portion in theobject having a pattern with a different height, which is a non-contactportion with the transparent base layer, is occupied by the air, therefractive index of the non-contact portion can be regarded as 1 (=n₀).

Furthermore, in the present application, the sheet 600 may be providedsuch that the light with the angle (θ_(B)) emitted from the second lightcontrol part 220 and incident on the transparent base layer may betotally reflected from the upper surface of the transparent base layerand then penetrate the upper surface of the light control layer 200.When the refractive index of the transparent base layer is larger thanthe refractive index of the light control layer 200, the totalreflection must not occur at the interface between the transparent baselayer and the light control layer 200, so that the angle θ_(B) cansatisfy the following relational expression 7.

θ_(B)<(180°/π)×sin⁻¹(n ₂ /n ₁)  [Relational Expression 7]

Relational Expression 7 above exemplarily defines a condition in whichthe total reflection does not occur at the interface between thetransparent base layer and the light control layer 200. In RelationalExpression 7 above, n₁ is the refractive index of the transparent baselayer, n₂ is the refractive index of the first light control part 210 orthe second light control part 220 in the light control layer 200, and n₁is larger than n₂.

In addition, the sheet 600 of the present application may be provided sothat when the light with the angle θ_(B) emitted from the second lightcontrol part 220 is totally reflected from the upper surface of thetransparent base layer, it can reach the lower base layer 300 orpenetrate the lower base layer 300. The light reaching the lower baselayer 300 or penetrating the lower base layer 300 can be recognized bythe sensor. In order that the light capable of being recognized by thesensor is present in the sheet 600, when the light with θ_(B) is totallyreflected from the surface layer of the transparent base layer andenters the upper surface of the lower base layer 300 via the transparentbase layer and the light control layer 200, the total reflection shouldnot occur at the interface between the light control layer 200 and thelower base layer 300. In this connection, θ_(B) can satisfy thefollowing relational expression 8.

θ_(B)<(180°/π)×sin⁻¹(n ₃ /n ₁)  [Relational Expression 8]

Relational Expression 8 above exemplarily defines a condition that thelight reaching the lower surface of the lower base layer 300 is present.In Relational Expression 8 above, n₁ is the refractive index of thetransparent base layer, and n₃ is the refractive index of the lower baselayer 300.

When the angle θ_(B) of the light totally reflected from the uppersurface of the transparent base layer as above satisfies RelationalExpressions 7 and 8 above, the sensor existing in the lower part of thesheet 600 can recognize the light reaching the lower base layer 300 orpenetrating the lower base layer 300, as shown in FIG. 1. That is, thesheet 600 of the present application allows the user's fingerprint to berecognized using a method of identifying a difference in light quantitybetween the light totally reflected from the upper surface of thetransparent base layer in contact with air and the light transmitted (ortransmission, scattering and reflection can occur at the same time) fromthe contact portion of the transparent base layer and the object amongthe light with an angle (θ_(B)) emitted from the second light controlpart 220.

As such, the present application does not directly use the light alwaystotally reflected in the sheet 600 for fingerprint identification.Specifically, when a part of the light with the angle θ_(A) providedfrom the first light control part 210 is converted into the light withthe angle θ_(B) different from θ_(A) by the second light control part220 and emitted toward the transparent base layer, so that the alwaystotally reflected light may exist, and the light emitted toward thetransparent base layer at the incident angle θ_(B) is totally reflectedfrom the upper surface of the transparent base layer in contact with anexternal object to the inside of the sheet 600 and transmitted (ortransmission, scattering and reflection can occur at the same time) tothe outside of the sheet 600, the present application uses the lightquantity difference of these lights for fingerprint identification. Thatis, the difference between the light quantity of the light totallyreflected from the non-contact portion with the fingerprint 700 andtraveling to the sensor and the light quantity of the light transmitted(or transmission, scattering and reflection can occur at the same time)from the contact portion with the fingerprint 700 and reduced, among thelights at the angle θ_(B), is used for fingerprint identification.

Furthermore, in the present application, the light with the angle θ_(B)is generated from the light always totally reflected in the sheet 600regardless of the presence or absence of the fingerprint 700. Therefore,in the present application, the light quantity of the light used foridentifying the fingerprint 700 can be kept constant by using the lightalways totally reflecting the inside of the sheet 600, and consequently,the light quantity difference between the light totally reflected fromthe interface of the transparent base layer and the air, and the lighttransmitted (or transmission, scattering and reflection can occur at thesame time) from the direct contact portion of the transparent base layerand the object, among the lights with the angle (θ_(B)), can be moreclearly recognized by the sensor. Besides, in the present application,the light totally reflected from the interface between the transparentbase layer and the air and the light transmitted (or transmission,scattering and reflection can occur at the same time) from the contactportion of the transparent base layer and the object, among the lightswith the angle (θ_(B)) generated regardless of the presence or absenceof the fingerprint 700, are used for fingerprint identification, so thateven if a number of fingerprint patterns are in contact with thetransparent base layer, they can be identified without being influencedby each other.

In one example, a projected area (S1) of the first light control part210 may be smaller than a projected area (S2) of the second lightcontrol part 220. In the present application, the term “projected area”may mean, on observing the sheet 600 from the upper part or the lowerpart in a direction parallel to the normal direction of its surface, anarea in which the relevant configuration is viewed, and for example, anorthogonal projection area. Therefore, the increase or decrease of theactual area due to the unevenness of the area comparison targetconfiguration or the like is not considered. Although not particularlylimited, S1:S2 may be in a range of 5 to 40:60 to 95.

In another example related to the present application, the presentapplication relates to an optical fingerprint recognition device(fingerprint scanner) or a fingerprint input device.

In one example, the device may further comprise a light source part 500.The light source part means a configuration capable of radiating lighttoward the sheet 600. The specific configuration of the light sourcepart is not particularly limited as long as the above function can beperformed. As in FIG. 1, the light source part 500 may be located on onesurface of the sheet 600 lower base layer 300, more specifically, on theopposite one surface of one surface of the lower base layer 300 wherethe first light control part 210 contacts. The light incident from thelight source part 500 is incident on the first light control part 210 ofthe light control layer 200 via the lower base layer 300, whereby thelight that can be always totally reflected in the sheet 600 can beprovided to the sheet 600. In one example, the light incident on thefirst light control part 210 may be vertical to the bottom surface ofthe first light control part 210. In the present application, the term“vertical” means a substantial verticalness in a range that does notimpair the desired effect, which is used, for example, in considerationof manufacturing error or variation, and the like. At this time, theerror or variation may be within ±10°, within ±8°, within ±6°, within±4°, within ±2°, within ±1°, within ±0.5°, within ±0.2°, or within±0.1°. In the case of the device comprising the sheet having the aboveconfiguration, even if a light source of a small area is used, theabove-described fingerprint recognition function can be sufficientlyperformed. In one example, the small area may be an area correspondingto or smaller than the first light control part 210.

In one example, the device may further comprise a sensor part 400. Thesensor part may mean a configuration for sensing the light penetratingthe lower base layer 300. The configuration of the sensor part is notparticularly limited as long as the above function can be performed,where a known sensor can be used. As in FIG. 1, the sensor part 400 maybe located on one surface of the sheet lower base layer 300, morespecifically, on the opposite one surface of one surface of the lowerbase layer 300 in which the second light control part 220 contacts. Asdescribed above, the light totally reflected in the transparent baselayer portion that directly contacts the fingerprint 700, except for thetotally reflected light in the sheet 600, can penetrate the lower baselayer 300 to reach the sensor part 400, where the sensor part 400 canrecognize the pattern of the object contacting the transparent baselayer, that is, the fingerprint 700, based on the light quantitydifference of the reached lights. In one example, the sensor part 400may be provided to have a transparent property. In another example, thesensor part 400 may have an area corresponding to the second lightcontrol part 220.

In one example, the device may further comprise a screen display part.The screen display part may be, for example, a configuration such thatan image or a moving image reproduced by the device can be viewed by theuser. As in FIG. 1, the screen display part may be positioned on onesurface of the sheet lower base layer 300, more specifically, theopposite one surface of one surface of the lower base layer 300 wherethe second light control part 220 contacts. In one example, the screendisplay part may have an area corresponding to the second light controlpart 220.

In another example, the device may simultaneously comprise a screendisplay part and a sensor part. In this case, the device maysequentially comprise a screen display part, a sensor part and a sheet,or may sequentially comprise a sensor part, a screen display part and asheet. In addition, any one of the screen display part and the sensorpart may also form one layer with the light source part.

In another example, the device may further comprise one part forperforming a display function and a sensor function at the same time. Inthis case, the one part may also form one layer with the light sourcepart.

FIG. 2 is an image of a fingerprint photographed using a sheet accordingto one embodiment of the present application. As the sheet used forphotographing, a laminate sequentially comprising a lower base layerhaving a refractive index of 1.41 for light having a wavelength of 532nm, a light control layer including a holographic film having arefractive index of 1.50 for light having a wavelength of 532 nm and aglass base layer (cover glass) having a refractive index of 1.51 forlight having a wavelength of 532 nm was used. In the case of the lightcontrol layer, it was produced using a known photopolymer film.Specifically, a diffraction pattern was recorded on the light controllayer, so that the first light control part could emit the incidentlight with 73° based on the normal to the sheet (transparent base layer)and the second light control part could emit some of the incident lightwith an angle of 45° based on the normal to the sheet (transparent baselayer. Thereafter, the sheet was irradiated with an external light with0° based on the normal to the sheet (transparent base layer), and theimage appearing at the bottom of the lower base layer by contacting afingerprint with the surface of the transparent base layer wasphotographed with a CCD (charge-coupled device).

As described above, the invention of the present application has beendescribed with reference to FIGS. 1 and 2 which are exemplaryembodiments of the present application, but the scope of protection ofthe present invention is not limited to the above-described specificembodiments and drawings. In addition, it will be understood by thosehaving ordinary knowledge in the technical field to which the presenttechnical field pertains that the inventions described in the claims canbe changed or modified variously within the technical spirit and scopeof the present invention as filed.

1. A sheet comprising: a lower base layer; and a light control layerpositioned on the lower base layer and having a first light controlpart, a second light control part, and a transparent base layersequentially, wherein the first light control part is provided so as toemit light incident on the lower surface of the first light control partat a first incident angle (θ₀) as light with a second incident angle(θ_(A)) different from the first incident angle (θ₀), and wherein thesecond light control part is provided so as to emit light incident onthe upper surface of the second light control part at the secondincident angle (θ_(A)) as light with the second incident angle (θ_(A))and light with a third incident angle (θ_(B)) different from the secondincident angle (θ_(A)).
 2. (canceled)
 3. The sheet according to claim21, wherein the first light control part is provided so as to emit thelight incident on the lower surface of the first light control part atthe first incident angle (θ₀) through the lower base layer as the lightwith the second incident angle (θ_(A)) different from the first incidentangle (θ₀) toward the transparent base layer, and wherein the secondlight control part is provided so as to emit the light incident on theupper surface of the second light control part at the second incidentangle (θ_(A)) through the transparent base layer as the light with thesecond incident angle (θ_(A)) and the light with the third incidentangle (θ_(B)) different from the second incident angle (θ_(A)) towardthe transparent base layer.
 4. The sheet according to claim 3, whereinthe first light control part and the second light control part compriseeach a diffractive optical element or a refractive optical element. 5.The sheet according to claim 4, wherein each of the first light controlpart and the second light control part comprises a respectiveholographic film.
 6. The sheet according to claim 4, wherein the lowerbase layer has a refractive index smaller than a refractive index of thelight control layer.
 7. The sheet according to claim 6, wherein adifference between the refractive index of the lower base layer and therefractive index of the light control layer is 0.1 or less.
 8. The sheetaccording to claim 6, wherein the lower base layer comprises an acrylictransparent pressure-sensitive adhesive layer or a silicone transparentpressure-sensitive adhesive layer.
 9. The sheet according to claim 6,wherein the transparent base layer has a refractive index larger thanthe refractive index of the light control layer.
 10. The sheet accordingto claim 9, wherein a difference between the refractive index of thetransparent base layer and the refractive index of the light controllayer is 0.05 or less.
 11. The sheet according to claim 9, wherein thetransparent substrate layer comprises glass or a polymer resin.
 12. Thesheet according to claim 3, wherein the sheet is provided such that thelight with the angle (θ_(A)) emitted from the first light control partcan be totally reflected from both of the upper surface of thetransparent base layer and the upper surface of the lower base layer bysatisfying:θ_(A)>(180°/π)×sin⁻¹(n ₀ /n ₁)and:θ_(A)>(180°/π)×sin⁻¹(n ₃ /n ₁) wherein, n₀ is the refractive index ofair, n₁ is the refractive index of the transparent base layer and n₃ isthe refractive index of the lower base layer.
 13. The sheet according toclaim 12, wherein the sheet is provided such that the light with theangle (θ_(A)) emitted from the first light control part can be totallyreflected from the upper surface of the transparent base layer and thenpenetrate the upper surface of the light control layer by satisfying:θ_(A)<(180°/π)×sin⁻¹(n ₂ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer, n₂ is the refractive index of the firstlight control part or the second light control part in the light controllayer, and n₁ is larger than n₂.
 14. The sheet according to claim 13,wherein when an object having a pattern with a different height contactsthe transparent base layer, the sheet is provided such that the lightwith the angle (θ_(A)) emitted from the first light control part istotally reflected from the upper surface of the transparent base layerthat the transparent base layer and the object contact directly bysatisfying:θ_(A)>(180°/π)×sin⁻¹(n _(h) /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer and n_(h) is the refractive index of theportion whose the object having a pattern with a different height is indirect contact with the transparent base layer.
 15. The sheet accordingto claim 14, wherein when the object having a pattern with a differentheight contacts the transparent base layer, the sheet is provided suchthat the light with the angle (θ_(B)) emitted from the second lightcontrol part can be totally reflected from the upper surface of thetransparent base layer in contact with air by satisfying the followingrelational expression 5 and the light with the angle (θ_(B)) emittedfrom the second light control part can be transmitted from the uppersurface of the transparent base layer that the transparent base layerand the object contact directly by satisfying:θ_(B)>(180°/π)×sin⁻¹(n ₀ /n ₁)and:θ_(B)<(180°/π)×sin⁻¹(n _(h) /n ₁) wherein, n₀ is the refractive index ofair, n₁ is the refractive index of the transparent base layer and n_(h)is the refractive index of the portion whose the object having a patternwith a different height is in direct contact with the transparent baselayer.
 16. The sheet according to claim 1, wherein the sheet is providedsuch that the light with the angle (θ_(B)) emitted from the second lightcontrol part can be totally reflected from the upper surface of thetransparent base layer and then penetrate the upper surface of the lightcontrol layer by satisfying:θ_(B)<(180°/π)×sin⁻¹(n ₂ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer, n₂ is the refractive index of the firstlight control part or the second light control part in the light controllayer and n₁ is larger than n₂.
 17. The sheet according to claim 16,wherein the sheet is provided such that the light with the angle (θ_(B))emitted from the second light control part can be totally reflected fromthe upper surface of the transparent base layer, pass through the lightcontrol layer and reach the lower surface of the lower base layer bysatisfying:θ_(B)<(180°/π)×sin⁻¹(n ₃ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer and n₃ is the refractive index of the lowerbase layer.
 18. The sheet according to claim 1, wherein the sheet isconfigured to be used for optical fingerprint recognition or opticalfingerprint input.
 19. An optical fingerprint recognition or inputdevice comprising: the sheet according to claim 1; and a light sourcepart, wherein the light source part contacts a surface of the lower baselayer opposite the light control layer, and wherein the light sourcepart emits vertical light towards the first light control part. 20-21.(canceled)
 22. The optical fingerprint recognition or input deviceaccording to claim 19, further comprising at least one of a screendisplay part or a sensor part.